Esophageal intubation and obturation to prevent aspiration of stomach contents during resuscitation has been disclosed by Giuffrida and Bizzarri, Amer. J. Surgery, Vol. 93, 329-334 (1957), Farley, Respiratory Therapy, pp. 95-99 (Nov./Dec. 1973), and in U.S. Pat. Nos. 3,683,908 and 3,841,319. A typical esophageal obturator airway consists of a cuffed endotracheal tube mounted through a face mask and provided with multiple openings in the upper one third of the tube at the level of the pharynx. In use, the tube is passed into the esophagus, the mask is seated upon the face, and the cuff is inflated. When mouth-to-tube or bag-valve-tube ventilation is performed, the air is discharged through the pharyngeal openings in the tube and passes down the trachea since the esophagus is blocked. The inflated cuff prevents gastric distension (by air) and regurgitation during resuscitation.
Esophageal obturator airway systems find increasing use in the emergency treatment of unconscious patients whose breathing has stopped or appears inadequate or likely to stop. Such resuscitation is needed for persons exposed to drowning or asphyxiation, who suffer from cardiac arrest, or who suffer from interrupted or inadequate respiration for any of a variety of other reasons.
In the treatment of cardiac arrest cases, external cardiac compression is commonly exerted in an effort to restore heart activity. Such compression promotes regurgitation and excessive lung inflation and promotes gastric inflation which also promotes regurgitation, with the potential danger that the stomach's contents might be aspirated into the lungs. The use of an esophageal obturator airway prevents occlusion of the natural airway, prevents aspiration, and assures the delivery of a high concentration of oxygen to the lungs. While the placement of such a system should be undertaken only be trained personnel, the procedure is one which does not require surgery (tracheotomy) or the services of an anesthetist with hospital facilities (unlike the insertion of a standard tracheostomy tube). Hence, the procedure is one which is being found increasingly useful in the emergency treatment of cardiac arrest patients.
Despite their advantage, prior esophageal obturator airway systems do have notable shortcomings and disadvantages. For one thing, proper ventilation of the patient depends on avoiding leakage of substantial quantities of oxygen through the mouth and nose. Quite obviously, is oxygen for resuscitation does not enter the patient's trachea but instead escapes through his nose or mouth, no artificially-induced respiration can occur. In an effort to reduce such backflow, a mask is ordinarily placed over the patient's nose and mouth; however, such masks are at best only partially effective. The problems are complicated by the fact that there are limitations on the maximum cross sectional dimensions of the main air tube, and the cuff-inflating tube and stomach tube with which it is associated, so that if adequate ventilation is to be provided, the loss of air needed for resuscitation must be avoided.
Other disadvantages of prior esophageal obturator airway systems include inadvertent tracheal intubation, blocking ventilation of the lung and laceration of the esophagus when the system is removed without deflating the esophageal balloon. The effectiveness of the inflated cuff as a sealing element requires that it firmly engage the esophageal wall; unfortunately, such firm engagement may have its own undesirable side effects since the inflated balloon is too large to pass throughout the upper esophagus without causing laceration.
Other references illustrating the state of the art are U.S. Pat. Nos. 3,889,688, 3,222,126, 3,460,541, 3,407,817, 3,826,635, 3,046,988 and 2,854,982.